RP312 The Animal That's Also an EnvironmentRP312 The Animal That's Also an Environment

 RP312 The Animal That's Also an Environment

It looks like a plant. It feels like a stone. But coral, which we consider a colorful setting for television programs about fish and other marine life, is actually an animal. And if we view a coral reef as a single organism, then it is by far the largest and oldest living thing on Earth.
Distant relatives of jellyfish and sea anemones, corals are invertebrates despite having a sort of skeleton. “Hard” corals’ skeletons, known as calices, are made of limestone. “Soft” corals, on the other hand, have wood-like skeletons. Only “hard” corals can form reefs. They do this by attaching themselves to rocks in shallow areas of tropical seas. A single coral can divide itself thousands of times, creating clone s which connect their calices to form a colony. This colony is in fact one animal, and can connect with other colonies to form a reef. Some reefs are believed to be over 50,000 years old!
If you've ever watched a TV show about ocean life, you probably think corals are very colorful. In fact they are clear, and get their rainbow tones from the billions of algae (plants) which attach to them. This relationship is highly beneficial to both parties. Corals get most of their food from the algae they host, but are also equipped with poisonous, hooked tentacles. These are used mostly at night, when the algae are asleep, to catch plankton and even small fish. That's right—corals are meat-eaters!
Since they must live near coastal areas, corals cover less than one percent of the ocean floor. Nevertheless, they support roughly 25 percent of all marine life. This is a problem, because reefs are rapidly falling victim to a variety of natural and man-made threats. Pollution, storms, global warming, boats, and the dumping of soil and sand into the world's oceans are all deadly to corals. Even a slight change in water temperature can cause corals to lose their algae covering, resulting in a potentially fatal condition known as bleaching.
If people cannot protect the world's oldest and largest organisms, what can we do? The time has come to start thinking about our impact on our environment—especially when that environment is itself an animal.